GitHub is an American company that provides hosting for software development version control using Git. It is a subsidiary of Microsoft, which acquired the company in 2018 for $7.5 billion.^[4] It offers all of the distributed version control and source code management (SCM) functionality of Git as well as adding its own features. It provides access control and several collaboration features such as bug tracking, feature requests, task management, and wikis for every project.^[5]

GitHub offers plans for free, professional, and enterprise accounts.^[6] Free GitHub accounts are commonly used to host open source projects.^[7] As of January 2019, GitHub offers unlimited private repositories to all plans, including free accounts.^[8] As of May 2019, GitHub reports having over 37 million users^[9] and more than 100 million repositories^[1] (including at least 28 million public repositories),^[11] making it the largest host of source code in the world.^[12]

GitHub was developed by Chris Wanstrath, P. J. Hyett, Tom Preston-Werner and Scott Chacon using Ruby on Rails, and started in February 2008. The company, GitHub, Inc., has existed since 2007 and is located in San Francisco.^[13]

On February 24, 2009, GitHub team members announced, in a talk at Yahoo! headquarters, that within the first year of being online, GitHub had accumulated over 46,000 public repositories, 17,000 of which were formed in the previous month alone. At that time, about 6,200 repositories had been forked at least once and 4,600 had been merged.

On July 5, 2009, GitHub announced that the site was being harnessed by over 100,000 users.

On July 27, 2009, in another talk delivered at Yahoo!, Preston-Werner announced that GitHub had grown to host 90,000 unique public repositories, 12,000 having been forked at least once, for a total of 135,000 repositories.^[14]

On July 25, 2010, GitHub announced that it was hosting 1 million repositories.^[15] On April 20, 2011, GitHub announced that it was hosting 2 million repositories.^[16]

On June 2, 2011, ReadWriteWeb reported that GitHub had surpassed SourceForge and Google Code in total number of commits for the period of January to May 2011.^[17]

On July 9, 2012, Peter Levine, general partner at GitHub investor Andreessen Horowitz, stated that GitHub had been growing revenue at 300% annually since 2008 "profitably nearly the entire way".^[18]

On January 16, 2013, GitHub announced it had passed the 3 million users mark and was then hosting more than 5 million repositories.^[19] On December 23, 2013, GitHub announced it had reached 10 million repositories.^[20]

In June 2015, GitHub opened an office in Japan that is its first office outside of the U.S.^[21]

On July 29, 2015, GitHub announced it had raised $250 million in funding in a round led by Sequoia Capital. The round valued the company at approximately $2 billion.^[22]

In 2016, GitHub was ranked No. 14 on the Forbes Cloud 100 list.^[23]

On February 28, 2018, GitHub fell victim to the second largest distributed denial-of-service (DDoS) attack in history, with incoming traffic reaching a peak of about 1.35 terabits per second.^[24]

On June 4, 2018, Microsoft announced it had reached an agreement to acquire GitHub for $7.5 billion.^[25] The purchase closed on October 26, 2018.^[26]

On June 19, 2018, GitHub expanded its GitHub Education by offering free education bundles to all schools.^[27][28]

On June 4, 2018, Microsoft announced its intent to acquire GitHub for US$7.5 billion, and the deal closed on October 26, 2018.^[29] GitHub will continue to operate independently as a community, platform and business. Under Microsoft, the service will be led by Xamarin's Nat Friedman, reporting to Scott Guthrie, executive vice president of Microsoft Cloud and AI. Current CEO Chris Wanstrath will be retained as a "technical fellow", also reporting to Guthrie. Microsoft had become a significant user of GitHub, using it to host open source projects and development tools such as Chakra Core, PowerShell, Visual Studio Code, and Windows Terminal and has backed other open source projects such as Linux, and developed Virtual File System for Git (VFS for Git; formerly Git Virtual File System or GVFS)—a Git extension for managing large-scale repositories (and itself has been adopted by GitHub).^[25][30]

There have been concerns from developers Kyle Simpson, JavaScript trainer and author, and Rafael Laguna, CEO at Open-Xchange over Microsoft's purchase, citing uneasiness over Microsoft's handling of previous acquisitions, such as Nokia's mobile business or Skype.^[31][32]

Some saw this as a culmination of Microsoft's recent changes in business strategy under CEO Satya Nadella, which has seen a larger focus on the sale of cloud computing services as its main line of business, alongside development of and contributions to open source software (such as Linux), as opposed to the Microsoft Windows operating system.^[33][4][30] Harvard Business Review argued that Microsoft was intending to acquire GitHub to get access to its userbase, so it can be used as a loss leader to encourage use of its other development products and services.^[34]

Concerns over the sale bolstered interest in competitors: Bitbucket (owned by Atlassian), GitLab (a commercial open source product that also runs a hosted service version) and SourceForge (owned by BIZX, LLC) reported that they had seen spikes in new users intending to migrate projects from GitHub to their respective services.^{[35][36][37][38]}

GitHub, Inc. was originally a flat organization with no middle managers; in other words, "everyone is a manager" (self-management).^[39] Employees could choose to work on projects that interested them (open allocation), but salaries were set by the chief executive.^[40]

In 2014, GitHub, Inc. introduced a layer of middle management.^[41]

GitHub.com was a start-up business, which in its first years provided enough revenue to be funded solely by its three founders and start taking on employees.^[42] In July 2012, four years after the company was founded, Andreessen Horowitz invested $100 million in venture capital.^[5] In July 2015 GitHub raised another $250 million of venture capital in a series B round. Investors were Sequoia Capital, Andreessen Horowitz, Thrive Capital and other venture capital funds.^[43] As of August 2016, GitHub was making $140 million in Annual Recurring Revenue.^[44]

GitHub's mascot is an anthropomorphized "octocat" with five octopus-like arms.^[45][46]

The character was created by graphic designer Simon Oxley as clip art to sell on iStock,^[47] a website that enables designers to market royalty-free digital images.

GitHub became interested in Oxley's work after Twitter selected a bird that he designed for their own logo.^[48] The illustration GitHub chose was a character that Oxley had named Octopuss.^[47] Since GitHub wanted Octopuss for their logo (a use that the iStock license disallows), they negotiated with Oxley to buy exclusive rights to the image.^[47]

GitHub renamed Octopuss to Octocat,^[47] and trademarked the character along with the new name.^[45] Later, GitHub hired illustrator Cameron McEfee to adapt Octocat for different purposes on the website and promotional materials; McEfee and various GitHub users have since created hundreds of variations of the character, which are available on The Octodex ^[114].^[49][50]

In March 2014, GitHub programmer Julie Ann Horvath alleged that founder and CEO Tom Preston-Werner and his wife Theresa engaged in a pattern of harassment against her that led to her leaving the company.^[51] In April 2014, GitHub released a statement denying Horvath's allegations.^[52][53] However, following an internal investigation, GitHub confirmed the claims. GitHub's CEO Chris Wanstrath wrote on the company blog, "The investigation found Tom Preston-Werner in his capacity as GitHub's CEO acted inappropriately, including confrontational conduct, disregard of workplace complaints, insensitivity to the impact of his spouse's presence in the workplace, and failure to enforce an agreement that his spouse should not work in the office."^[54] Preston-Werner then resigned from the company. In 2017 more allegations were made of discriminatory and unsupportive behavior at GitHub by a developer who had been recruited following a commitment by GitHub to improve its diversity and inclusivity.^[55]

Development of the GitHub platform began on October 19, 2007.^[56][57][58] The site was launched in April 2008 by Tom Preston-Werner, Chris Wanstrath, P. J. Hyett and Scott Chacon after it had been made available for a few months prior as a beta release.^[59]

Projects on GitHub can be accessed and manipulated using the standard Git command-line interface and all of the standard Git commands work with it.

GitHub also allows registered and non-registered users to browse public repositories on the site.

Multiple desktop clients and Git plugins have also been created by GitHub and other third parties that integrate with the platform.

The site provides social networking-like functions such as feeds, followers, wikis (using wiki software called Gollum) and a social network graph to display how developers work on their versions ("forks") of a repository and what fork (and branch within that fork) is newest.

A user must create an account in order to contribute content to the site, but public repositories can be browsed and downloaded by anyone.

With a registered user account, users are able to have discussions, manage repositories, submit contributions to others' repositories, and review changes to code. Github began offering unlimited private repositories at no cost in January 2019 (limited to three contributors per project). Previously, only public repositories were free.^[60][61][62]

The fundamental software that underpins GitHub is Git itself, written by Linus Torvalds, creator of Linux. The additional software that provides the GitHub user interface was written using Ruby on Rails and Erlang by GitHub, Inc. developers Wanstrath,^[63] Hyett, and Preston-Werner.

GitHub is mostly used for code.

In addition to source code, GitHub supports the following formats and features:

GitHub's Terms of Service do not require public software projects hosted on GitHub to meet the Open Source Definition. For that reason, it is essential for users and developers intending to use a piece of software found on GitHub to read the software license in the repository (usually found in a top-level file called "LICENSE", "LICENSE.txt", or similar) to determine if it meets their needs. The Terms of Service state, "By setting your repositories to be viewed publicly, you agree to allow others to view and fork your repositories."^[69]

GitHub Enterprise is a self managed version with similar functionalities to GitHub's public service, it can run on your own premises or on a cloud provider, it is available since November 2011 ^[70].

GitHub Pages is a static web hosting service offered by GitHub since 2008 to GitHub users for hosting user blogs, project documentation,^[71][72] or even whole books created as a page.^[73]

All GitHub Pages content is stored in Git repository, either as files served to visitors verbatim or in Markdown format. GitHub is seamlessly integrated with Jekyll static web site and blog generator and GitHub continuous integration pipelines. Each time the content source is updated, Jekyll regenerates the website and automatically serves it via GitHub Pages infrastructure.^[74]

As with the rest of GitHub, it includes both free and paid tiers of service, instead of being supported by web advertising. Web sites generated through this service are hosted either as subdomains of the github.io domain, or as custom domains bought through a third-party domain name registrar.^[75]

GitHub also operates other services: a pastebin-style site called Gist ^[59] that is for hosting code snippets (GitHub proper is for hosting larger projects).

Tom Preston-Werner presented the then-new Gist feature at a punk rock Ruby conference in 2008.^[76] Gist builds on the traditional simple concept of a pastebin by adding version control for code snippets, easy forking, and SSL encryption for private pastes. Because each "gist" has its own Git repository, multiple code snippets can be contained in a single paste and they can be pushed and pulled using Git. Further, forked code can be pushed back to the original author in the form of a patch, so gists (pastes) can become more like mini-projects.

GitHub launched a new program called the GitHub Student Developer Pack to give students free access to popular development tools and services.

GitHub partnered with Bitnami, Crowdflower, DigitalOcean, DNSimple, HackHands, Namecheap, Orchestrate, Screenhero, SendGrid, Stripe, Travis CI and Unreal Engine to launch the program.^[77]

In 2016 GitHub announced the launch of the GitHub Campus Experts program^[78] to train and encourage students to grow technology communities at their universities.

The Campus Experts program is open to university students of 18 years and older across the world.^[79] GitHub Campus Experts are one of the primary ways that GitHub funds student oriented events and communities, Campus Experts are given access to training, funding, and additional resources to run events and grow their communities.

To become a Campus Expert applicants must complete an online training course consisting of multiple modules designed to grow community leadership skills.

GitHub also provides some software as a service integrations for adding extra features to projects. Those services include:

Site: https://github.community/

^[115]

GitHub maintains a community forum where users can ask questions publicly or answer questions of other users.

Site: https://github.com/sponsors ^[116]

GitHub Sponsors allows users to make monthly money donations to projects hosted on GitHub.

The public beta was announced on May 23, 2019 and currently the project accepts wait list registrations.

The Verge said that GitHub Sponsors "works exactly like Patreon" because "developers can offer various funding tiers that come with different perks, and they’ll receive recurring payments from supporters who want to access them and encourage their work" except with "zero fees to use the program". Furthermore, GitHub offer incentives for early adopters during the first year: it pledges to cover payment processing costs, and match sponsorship payments up to $5,000 per developer. Furthermore, users still can use other similar services like Patreon and Open Collective and link to their own websites.^[80][81]

On July 25, 2019, a developer based in Iran wrote on Medium about how GitHub blocked his private repositories, and prohibited access to GitHub Pages.^[82] Soon after, GitHub confirmed that it was now blocking developers in Iran, Crimea, Cuba, North Korea, and Syria from accessing private repositories. ^[83] However, GitHub reopened access to GitHub Pages days later, for public repositories regardless of location. It was also revealed that using GitHub while visiting sanctioned countries could result in similar action occurring on a user's account. GitHub responded to complaints and the media through a spokesperson, saying:

Developers who feel that they should not have restrictions can appeal for the removal of said restrictions, including those who only travel to, and not reside, in those countries.

GitHub has forbidden the use of VPNs and IP proxies to access the site from sanctioned countries, as purchase history and IP addresses are how they flag users, among other sources.^[86]

On December 3, 2014, GitHub was blacklisted in Russia because GitHub initially refused to take down user-posted suicide manuals.^[87] After a day, Russia withdrew its block.^[88]

On December 31, 2014, GitHub was blocked in India (along with 31 other websites) over pro-ISIS content posted by users.^[89] On January 10, 2015, GitHub was unblocked.

On March 26, 2015, GitHub fell victim to a massive DDoS attack that lasted for more than 118 hours.^[90] The attack, which appeared to originate from China, primarily targeted GitHub-hosted user content describing methods of circumventing Internet censorship.^[91][92][93]

On October 8, 2016, GitHub access was blocked by the Turkish government to prevent email leakage of a hacked account belonging to the country's Energy Minister.^[94]

On July 25, 2019, GitHub started blocking developers in countries facing US trading sanctions.^[84]

Some prominent open source organizations and projects use GitHub as a primary place for collaboration, including: